The goal is to prepare monoclonal antibodies that bind to human prostate adenocarcinoma membrane antigens and to use these antibodies to biochemically characterize their target antigens. The usefulness of these antibodies in the diagnosis and therapy of prostatic cancer will be evaluated. We have successfully derived hybridomas using two well-established human prostate adenocarcinoma cell lines and prostatic adenocarcinoma tissue specimens as immunogens. The monoclonal antibodies isolated from a hybridoma clone (83.21) resulting from the fusion of P3X63/Ag8 mouse myeloma cells and lymphocytes activated against DU145 human prostate cancer cells have been the most extensively studied antibodies to date. This antibody reacts strongly to the DU145 and PC-3 prostate adenocarcinoma cell lines as well as to several transitional cell bladder carcinoma cell lines. An intriguing finding has been that this antibody cross-reacts to seven human cell lines transformed by several different strains of cytomegalovirus (CMV) but does not react to cell lines transformed by herpes, SV40, or Epstein-Barr viruses. The antibody also does not react with the normal human cell lines used for CMV transformation. Immunoperoxidase analysis indicated that this antibody was reactive to 14 of 19 primary and 1 of 6 metastatic prostate adenocarcinomas. The 83.21 antibody also bound 2 of 4 bladder tumors but did not bind to 9 benign prostatic hyperplastic or 30 normal tissues. The 83.21 antibody does not react with a number of well-known human tumor markers. Biochemical characterization of the 83.21 antibody is in progress, and reliable data have been obtained using monoclonal antibody affinity chromatography. The antigenic target of the 83.21 monoclonal antibody on DU145 cells appears to be a membrane glycoprotein with a Mr = 180 kilodaltons. The glycoprotein appears to have an alpha2 beta2 subunit composition with a 60 kilodalton heavy chain and 30 kilodalton light chain. The subunits are disulfide-linked to each other. (2)